Structure Function Relationships in Milk-Cotting Enzymes: Pepsin-A Model

摘要

Numerous studies examining functionality on a mechanistic level of food-related proteins have recently been undertaken using genetic engineering techniques. Research in our laboratory has concentrated on the genetic engineering of pepsin, a milk-clotting enzyme which belongs to aspartic proteinases, in order to determine the role of specific amino acids/regions of pepsin, and its zymogen, pepsinogen, on structure and catalytic activity. Results from these studies indicated that site-directed mutagenesis of regions both adjacent (e.g., flap loop region) and remote (e.g., prosegment of the zymogen, surface of the enzyme) t the active site were critical to catalytic parameters and were reflected in structural changes as determined by circular dichroism and molecular modelling. Information gleaned from such studies may allow us to redesign enzymes, as well as other food-related proteins, for a particular function and/or environment in a predictable manner.